The invention relates to a microscope, in particular a confocal microscope or confocal laser scanning microscope.
Conventional microscopes, and indeed confocal microscopes or confocal laser scanning microscopes as well, have been disclosed for years in the art, so it is not necessary to provide a specific description of these microscopes here. In the confocal-laser scanning microscope, the beam scanning direction provides a preferred direction for the measurement or scanning. Since complicated structuresxe2x80x94such as modern semiconductor designsxe2x80x94increasingly do not have rectangular structures, however, their measurementxe2x80x94in industryxe2x80x94necessitates rotating these structures or the object which is configured in such a way relative to the scanning beam.
Furthermore, for measurement purposes it may be necessary, in principle, to perform rotation of the object in order, for example, to be able to compare any desired structural features with predetermined structural patterns in the context of quantitative structural analysis. At any rate, in a wide variety of fields of application there is a fundamental requirement of being able to rotate the image as desired, for which purpose it has been necessary to rotate the object heretofore.
When the object is rotated about an arbitrary point, the object has to be rotated, on the one hand, and displaced, on the other hand, in such a way that this arbitrary point lies at the pivot point of the object, namely in order to obtain the center point of the image. However, the rotation and, if appropriate, simultaneous displacement of the object leads to a complex movement entailing a considerable outlay on setting.
As seen per se, an apparatus and a method for projecting images for use in television or video technology are disclosed in WO-A1-94/08425, according to which, during image projections, rotations are performed for the purpose of compensating for horizontal movements.
The present invention is based on the object, therefore, of configuring and developing a microscope, in particular a confocal microscope or confocal laser scanning microscope, in such a way that an object can be measured from a plurality of angular positions whilst avoiding rotation of the object to be measured.
The invention, microscope or confocal microscope or confocal laser scanning microscope achieves the above object by means of the features described herein, according to which the invention""s microscope, confocal microscope or confocal laser scanning microscope is characterized by an optical arrangement for image rotation, said optical arrangement being provided in the beam path of the microscope.
The invention marks a departure, in the case of microscopes of the type discussed here, from rotating the object itself, or simultaneously displacing it in the process, in order to measure the object at different beam angles. Rather, optical rotation is now performed, namely by means of an optical arrangement for image rotation, said optical arrangement being provided in the beam path of the microscope, with the result that the object itself remains positioned in an unchanged manner. Consequently, repeated setting or calibration of the object is no longer necessary.
The optical arrangement for image rotation may be, for example, a prism designed in a wide variety of ways; thus, by way of example, a Dove prism or an Abbe prism. Further suitable prisms can be used for this purpose, it being essential that the prism is used as a quasi monolithic module for image rotation.
In the context of an alternative configuration of the optical arrangement for image rotation, the latter could be a mirror arrangement, preferably an arrangement with an odd number of mirrors, as is the case with the xe2x80x9cKxe2x80x9d mirror. More complicated configurations are conceivable here, it being necessary to take account of the fact that the light losses increase as the number of mirrors increases. In this respect, an arrangement with three mirrors presents itself as an advantageous configuration.
With regard to concrete localization of the arrangement for image rotation, it is advantageous in the context of an especially simple configuration if said optical arrangement is arranged in the parallel beam path of the microscope. Specifically, the optical arrangement for image rotation could be arranged between the tube lens and the objective, namely in the infinite beam path of the microscope.
Likewise, it would alternatively be conceivable for the optical arrangement for image rotation to be arranged downstream of the eyepiece and/or the tube lens, this resulting in inconsiderable requirements of the angular accuracy of the arrangement. In the context of such a configuration, the arrangement for image rotation would easily be able to be retrofitted. The requirement of synchronous rotation of the two eyepieces would certainly be disadvantageous in this case.
In the context of a further configuration option, the optical arrangement for image rotation could serve for rotating all the scanned and video images fed into the microscope by a laser scanner. To that end, the optical arrangement for image rotation could be arranged between a scanning lens and a scanning mirror of the laser scanner. This configuration is advantageous in so far as here there is a substantially smaller degree of angular sensitivity, as exists when the rotor is arranged between tube lens and objective.
In order to avoid interference when coherent light sources are used, the laser scanner could have stationary beam splitters which are sufficiently thick or sufficiently wedge-shaped, with the result that the internal reflections of the original beams run in a manner spatially separated from the original beams. Interference phenomena are thereby suppressed.
Furthermore, a separate adjustment apparatus could be provided for the purpose of minimizing the beam offset during rotation of the arrangement.
Finally, in a further advantageous manner, provision is made of an axially moveable objective and/or an axially moveable objective turret for taking z-sections in arbitrarily oriented directions.